Abstract
The pitting potentials of type 316 stainless steel (SUS316) were measured in solutions whose composition simulated typical brine, concentrated brine and mother liquor in salt production. By comparing the pitting potential measured under the various conditions, we assessed how the susceptibility of the stainless steel to pitting corrosion was affected by a solution's chloride-ion concentration, pH and temperature.
Within the near-neutral pH region, the pitting potential scarcely depended on the solution's pH. However, in the higher pH region, the pitting potential markedly increased with pH when it exceeded a critical level that was determined by the combination of the environmental factors. The pitting potentials as measured by a potential scan method, V'C100 and the intensities of each environmental factor showed the following relation within the solution's composition used in this study;
V'C100=-0.218log (Cl-) +535/T+0.0224pH-1.48
Cl-, T and pH designate the chloride ion concentration in molality (mol/kg-H2O), the temperature (K) and the pH value of the solution, respectively.
